Abstract

Abstract: Embryology of Ipomaea macrantha R. & S., Ipomaea hederifolia L. and Ipomaea pes-caprae (L.) Sweet. Has been investigated. Anther wall development is of the Dicotyledonous type and at maturity consists of the endothecium, 1-2 middle layers and secretory tapetum. Tapetum is also formed from the connective. Microspore mother cells undergo simultaneous divisions and produce and are mostly 2-celled at anthesis. Rarely 3-celled grains occur in I. macrantha. Overy is superior, biocarpellary, syncarpous and bilocular with two anatropous, unitegmic and crassinucellate ovules in each locule on axile placentation. Archesporium is single celled. Megaspore mother cell undergo meiotic division and produce a linear tetrad of megaspores of which the chalazal one develops into an 8-nucleate embryo sac of the Polygonum type. Antipodals are ephemeral. Fertilization is porogamous. Syngamy and triple fusion occurs almost stimultaneously. Endosperm is nuclear. Embryo development is of the sherardia variation of the Solanad type. Suspensor is large and haustorial.

中文摘要

觀察大牽牛花(Ipomaea macrantha)、原葉蔦蘿(Ipomaea hederifolia)及馬鞍藤(Ipomaea pes-caprae)這三種植物的胚胎發生過程，它們的花藥壁發育都屬於雙子葉植物型，即是在成熟實為有內殼、一至二層的中間層及分泌型的營養層所組成。營養層由藥隔處逐漸形成。小孢子母細胞會同時進行減數分裂，之後產生四面體形、十字對生的四分子孢子，花粉為橢圓形、外壁具刺紋、多孔，在花期時多以兩個細胞型存在。在大花牽牛中則偶有三個細胞的。 子房上位、具有兩個心皮、為合生型、內有兩室，每室含有兩個倒生、單一種皮、珠心肥厚的胚珠，為中軸胎座，孢原為單細胞。大孢子母細胞進行減數分裂後產生一個線型的四分大孢子，靠近合點的一個會發育成蓼型的七細胞八核之胚囊。反足細胞為暫存的，授精作用在珠孔端發生。雙重授精的過程幾乎是同時。胚乳為無壁式的。胚胎的發育與茄科型不同。懸柄大且有吸足的功能。